A liquid crystal display device includes, for example, an active matrix substrate in which a thin film electrical element, such as a thin film transistor (hereinafter referred to as “TFT” in some cases), is provided in each sub-pixel which is the minimum unit of an image; a counter substrate provided so as to face the active matrix substrate; and a liquid crystal layer provided between the active matrix substrate and the counter substrate.
In recent years, in a display device such as a liquid crystal display device, instead of using a glass which has been used in the past, an active matrix substrate using a resin substrate has been proposed.
For example, Patent Literature 1 has disclosed a display device in which a main substrate on which active elements are formed is a laminate film including an insulating film formed of a resin material having a high heat resistance and a metal thin film formed of a metal or an alloy having a smaller coefficient of linear expansion than that of the insulating film, and the total number of the insulating film and the metal thin film is odd and at least three.
In addition, Patent Literature 2 has disclosed a silicon thin film transistor in which buffer layers are formed on two surfaces of a substrate, a silicon channel (silicon channel) is formed in a one buffer layer (located at one side), a gate insulating layer is formed on the silicon channel, and a gate is formed on the gate insulating layer.